US2498763A - Magnetron - Google Patents

Description

Feb. 28, 1950 J. W. MCNALL 2z BY ATTORN EY 'Patented Feb.' 28.1950

MAGNETRON John W. McNall, East Orange, N. J., assigner to Westinghouse Electric Corporatiom-East Pittsburgh, Pa., a corporation of Pennsylvania Application vlune 15, 1944, Serial No. 540,453

(Cl. Z50-27.5)

11 claims. l

rihis invention relates to magnetrons and more particularly to tuning means therefor.

An object of the invention is to provide an improved and convenient means. for vtuning a magnetron.

Another .object is to .provide for a wide range of tuning for a-magnetron.

A further object is to provide a rotative or oscillatory tuning means and 'with its taxis lof movement coincident with vthe axis of the cathode and anode.

A still further object of the invention .is to provide a simple, light and .readily Iassembled rotor for the tuning 'mea-ns.

Further objects l'of the invention will appear to those skilled in the art to which it appertains both by direct recitation thereof as the description proceeds and by inference from the-context.

Referring to the accompanying drawing in which like numerals of reference indicate like parts throughout the several views;

Figure 1 is a, cross section of 1a magnetron in which my invention is employed, the section being taken just below the end plate and longitudinally of the tuning control means.

Figure 2 is a section on 'line .II--II' oi Fig. 1;

Fig-ure 3 is a Icross section on line III-III ofv Fig. 2;

Figure 4 is a perspective view ofthe rotor con-V stituting an essential part of the' invention;

Figure 5 is a cross section of one of the rotor varies; and

Figure 6 is a cross section ofa modified construction of rotor vane.

In the specific embodiment of the invention illustrated invsai'd drawing, the vreference numeral lli designates a. magnetron body portion shown as cylindrical, of metal, and closed by metallic end plates or caps I I. The particular magnetron here shown provides a plurality-of internal radially disposed xed metallic venes I 2l ofi less length than the cylindrical interior of the' body portion so as to leave 'end spaces I3 between the ends of the vlanes and the end plates II. Said fired vanes have-'their inner longitudinal edgesseparated from each other and directed toward', a cylindrical centralized cathode Il' having usual internal heating filament I'51 The vanes converge toward each other, viewed from the exterior, and thus define between successive variesy of thea-nnular series thereof cavities having approximately trapezoidal cross-sectional shape, .and for convenience of reference referred tolas the resonant cavities I6. The region aroundthe cath-y ode 'and within the inner edges: of the several varies is herein designated the cathode cavity I1. The iixed vanes, and particularly the inner edges thereof, constitute the anode. Input for the lament I5 is by way of lead-in structures I8 of usual construction, and output for derived energy is by way of a coaxial line I9 which is shown having an appropriate loop 20 in one of the resonant cavities.

In carrying out the present invention, the tuningmeans includes a rotor, shown alone in Fig. 4, said rotor being fabricated with twoparallel rings 1l', which may be either of metal or oi insulator material, centeredA on a common axis, which in use is coaxial with the axis of the cathode and anode of the magnetron. When the rotor is assembled in the magnetron, said rings are within the aforementioned end spaces I3.. Extending between the rings, in parallelism to the said axis, are a plurality oi metallic vanes 22 evenly spaced in an annular series and in radial planes, except that there may be omission of or modication of one vane of the rotor corresponding to the cavity having the output loop, but otherwise there is shown one vane on the rotor for each resonant cavity of the magnetron. The number of vanes employed.. however, may be varied as desired.. The rotor vanes are carried atv their ends by and revolved, with restricted amplitude, by the said rings. rotor vanes have the same relation. to their respective resonant cavity walls at anygiven position of the rotor, and rotation of the rotor makesv a corresponding change of position for all of said rotor vanes with respect to the fixed varies. For instance, one position of the rotor vanesis shown in solid lines in Fig. 3 and another position thereof is shown by adjacent dotted lines. Furthermore, the rotor vanes are free of contact from they cylindrical wall of the magnetron body, and havey ay width less than that of the xed varies so as not to project into the central or cathode cavity. The said rotor vanes are eachk likewise quite thin and may be made with opposite faces parallel as shown in Figs. 1 to 5, or may be a vane 22s,. which is tapered in cross section asf shown in Fig. 6, in which event the thicker edge is parallel toA and next the cylindrical wall of the body portion. If desired, the rotor vanes may be covered with a dielectric material, such as mica or glass, to increase the capacity between rotor and 'fixed vanes andN prevent sparking therebe tween.

The rotor has, as a part thereof, a spider mount at' eachend, each said mount having a hub23 from the periphery of which radiate: sev*- erall wirelegs 2l?, outerfendportions of whiclrz are bent into parallelism with the hub axis and in a direction toward the ring of the rotor. These end portions of said legs 24 are embedded in, riveted tc or otherwise secured to the said ring. Preferably, the said legs are electrically discontinuous one from another to avoid setting up induction current ow, and are shown each embedded separately in the hub which is indicated as of insulating material. Projecting axially outward from the hub' 23 is a pivot pin 25, the projecting end of which is shown seated in a bushing 26 carried at the middle of the inner face of end plate or cap Il.

In order to rotatively adjust the rotor, either clockwise or counterclockwise, a lever 21 is shown as having an inner forked end engaging the bent leg portion of one of said spider legs 24, said lever projecting in a generally radial direction from engagement with said leg to a distance outside of the magnetron body. Said lever, however, is enclosed within a housing 28 which includes a flexible portion 29 by which vacuum sealing of the magnetron interior is maintained but permitting said lever to pass to the exterior and be there under control of the operator.

Inasmuch as said lever must be held securely in adjusted position, retaining as well as adjusting means are provided for the purpose. As shown, the lever has a head 3Q thereon to which ilexible housing portion 2S is secured and also on which is secured a bracket 3i which provides a forked end laterally of the lever. A sleeve 32 extending in the same general direction' as the lever is pivotally carried by saidv forked end so as to swing in the sameplane inl which the lever swings. Longitudinally through the sleeve, and in threaded engagement therewith, is an adjusting screw 33 having a ball and socket connection with a bracket 34 fixed with respect to the magnetron. The outer end of the adjusting screw has a knurled'knob 35 or other convenient manipulation means.

It is believed the theory of tuning by shifting the rotor vanes into different relations with respect to the xed vanes or cavity walls will be in accordance with the following two possible explanations. closer to a fixed wall of the cavity resonator, the capacity between said wall and vane will be increased. Change of capacity will result in a change in the resonant frequency of that cavity resonator, thereby changing the frequency of the oscillations generated by the magnetron. Secondly, the tuning or rotor vanes and supporting ring or rings have a resonant frequency so that oscillations which may be generated therein react with the normal oscillations of the cavity resonators resulting in a change of frequency of the latter oscillations, and hence of the oscil-. lations generated by the magnetron.

I claim:

Al. In a magnetron having a circular series of cavity resonators, and having intervening walls separating said resonators, tuning means for said magnetron comprising a vane within one of said resonators and'extending in the same genera-l direction as the said intervening walls bounding that one'of said resonators and movable in its entirety in parallelism to itself to closer proximity to one' intervening wall than to the other intervening wall of the resonator in which said vane is located.

2. In a magnetron-having a cavity resonator, tuning means comprising a vane in said cavity resonator extending substantially from end to First, asa rotor vane is brought end of said resonator dividing the resonator space into two parts, means at an end of said resonator Cllr supporting said vane, said means being rotatable in a direction normal to the vane for revolving said vane within the connes of said resonator and thereby changing the ratio of the two parts of the resonator space, and adjustable means in operative engagement with said vane supporting means for rotating said means and revolving said vane.

4. In combination with a magnetron having an axis and having a plurality of cavity reso-'g nators longitudinallyparallel to the axis of the magnetron, tuning means therefor comprising a rotor having vanes disposed longitudinally in said resonators parallel to said axis and substantially in planes with said axis, said rotor having limited amplitude of rotation and all of said vanes being iixed in relation to each other and simultaneously movable with correspondingly limited amplitude in said resonators in which they are disposed.

. 5. Tuning means for a magnetron comprising a rotor having a ring, a hub coaxial with Ysaid ring, legs extending from said hub to said ring,

andv vanes xed on therewith.

6. Tuning means for a magnetron comprising a plurality of rings in spaced parallel planes and Centered on a common axis perpendicular to said planes, hubs offset outwardly from said planes and coaxial with said axis, legs connecting each hub with lone of said rings, and vanes extending longitudinally between said rings and fixed at their ends to said rings. y '7. Tuning means for a magnetron comprising a plurality of -rings in spaced parallel planes and centered on a common axis perpendicular to said planes, hubs oiset outwardly from said planes and coaxial with said axis, coaxial pins on the hubs projecting outwardly from each for rotative support thereof, legs connecting each hub with one of said rings, and vanes extending longitudinally between said rings and fixed at their ends to said rings.

8. Tuning means for a magnetron comprising a plurality of rings in spaced parallel planes and centered on a common axis perpendicular to said planes, hubs of insulative material oiTset outwardly from said planes and coaxial with said axis, legs connecting each hub with one of said rings, and` vanes extending longitudinally be-, tween said rings and fixed at their ends to saidl rings. 1 v

9. In combination with an enclosure of an electron discharge device and a movable part within said enclosure, an operating mechanism. for said movable part comprising a housing projecting from and secured to said enclosure, saidhousing having an opening longitudinally there-r through, a lever in and longitudinal of said open-4 ing and pivoted to said housing, a exible sleeve sealed at one endfto the housing and sealed aty its otherl end to the outer .end of the leven' thereby enablingvacuum -to be maintained said ring and rotatable said enclosure and housing and enabling said lever to be swung exterior to the housing and operate said movable part within the enclosure; L 10. In combination with an enclosure' of an .l

electron discharge device and a movable partij Within said enclosure, an operating mechanism'vl for said movable part comprising a housing proing and pivoted to said housing, a flexible sleeveA sealed at one end to the housing and sealed at its other end to the outer end ofthe lever, thereby,

enabling vacuum to be maintained in said en-k closure and housing and enabling said lever to be swung exterior to the housing and operate said movable part within the enclosure, and means at 11. In combination with an enclosure of ani electron discharge device and a movable partA means pivoting said lever to the housing, and

means iexibly connecting the lever at an exteriorly projecting part thereof to said housing and providinga vacuum tight seal for the opening throughjfthehousing, said flexible means enabling said lever to"`-be swung and at the same time maintain thevacuum therein and in the housing and enclosure.

JOHN W. MCNALL.

REFERENCES CITED The following references are of record in the le of this patent:`A

Within said enclosure, an operating mechanismA for said movable part comprising a housing projecting from and secured to said enclosure, said housing having an opening therethrough, a lever in and projecting from said opening of the housing into the interior of said enclosure and in operative engagement with the part therein to be moved, and said lever projecting to the exterior of said housing through said opening,

UNrrEDv STATES PATENTS Number Name Date 318,461 Gardiner May 26, 1885 932,111 lFessenden Aug. 24, 1909 1,309,753 De Forest July 15, 1919 1,812,828 Gray; June 30, 1931 2,063,137 Whitenack Dec. 8, 1936 2,145,225 Kolster et al Jan. V24, 1939 2,243,537 Ryan; May 27, 1941 2,281,717 Samuel May 5, 1942 2,298,949 Litton Oct. 13, 1942 2,304,186 Litton Dec. 8, 1942 2,323,735 Tawney July 6, 1943 2,356,414 Linder Aug. 22, 1944 2,391,016 Ginzton et al. Dec. 18, 1945 2,418,469 I-Iagstrum Apr. 8, 1947 2,424,496 Nelson July 22, 1947

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